Process of manufacturing thin threads of artificial silk of highest degree of fineness from viscose



Patented Mar. 2, 1926. p

1,575,052. UNITED STATES PATENT OFFICE.

LEOPOLD HESBE, 01' BABMEN AND HEBMANN RATHER-T, OI ELBERFELD, GERMANY.

PROCESS 0]? WUFACTURINGYTHIN THREADS OF ARTIFICIAL SILK OF HIGHEST:

- DEGREE OF FINENESS FROM VISCOSE.

R0 Drawing.

To all whom it may aom'em:

Be it known that we, LEOPOLD Hesse, a citizen of the German Empire,residing at Barmen, Germany, and HERMANN RATHERT,

a citizen of the German Empire, residing at Elberfeld, Germany, haveinvented certain new and useful Processes of Manufacturing Thin Threadsof Artificial Silk of Highest Degrees of Fineness from Viscose (forwhich we have filed applications in Germany February 28th, 1921;Holland, September 1st, 1921), of which the following is. aspecification.

Thin threads of artificial silk from viscose of very high degrees offineness could only be obtained heretofore from viscose's'olutions asheretofore known by keeping within the limits of sharply definedconditions of maturing of such solutions whichshould have very exactsharply defined compositions with a view of obtaining certain 1ndividual thread numbers-or titers. Thus for instance, by the ejection ofviscose solutions from nozzles with apertures of one-tenth millimeterdiameter and by. employing a velocity of the reeling mechanism up tofifty meters per minute.

l/and by using acid spinning baths with an excess of neutral sulfateover the bisulfate present threads were obtained hav-- ing individualnumbers down to four denlers; while sulphate highly glossy threads wereobtained of a size numbering down to 2 deniers;'

3/baths of sulfate of ammonia mixed with but little acid yield extremelyfine threads of viscose artificial silk having individual thread numbersbelow 2 deniers.

Now, as distinguished from this previous state of the art our inventionrelates to a process according towhich, .aside .from threads above fivedeniers, hi hly lossy very thin artificial silk threads befiiw .5deniers, as well as glossy threads of artificial silk of high degrees offineness below two deniers may be obtained by employing the samespinning bath and the same viscose.

of the same degree of maturity, and with nozzles having apertures of thesame diameter.

Our process substantially resides in the precipitation of certainsolutions of viscose Serial No. 536,865.

by means of a spinning bath containing sulfate of soda, and showing adegree of acidity of about '15 to 16 percent of sulphuric acid at aspecific gravity of about 1.39 to 1.45 at 40 degrees centigrade, theprecipita- .the separation ofthe alkali-cellulose from the liquidprevious to the action of carbonbisulphide as a solvent forthe xanthateproduced. In a general way such solutions of viscose are obtained byfirst preparing the xanthogenate of cellulose by the treatment withcarbon-bisulfide of alkali-cellulose at the exclusion of the action ofoxygen from the air, and preferably with the addition of reducingagents, and then dissolving such xanthogenate in pure or previously usedliquors containing reducing agents, these solutions being thenprecipitated as hereinbefore referred to. The products obtained may beconverted into threads by using nozzles with apertures of one tenthmillimeter diameter, and' havin withdrawing velocities for the escapingt reads up to.50 meters. The maturity and the age of the viscose tobesubmitted to the spinning operation with this invention are capable ofvariation within unsurpassedly wide limits, so that by this new processa very important improvement over the present state of the art isrealized. lVhile, with the ordinary kinds of viscose and by usin theusual acid precipitating baths, the duration of maturity for the viscoseshould not vary for more than about twelve hours at the ordinaltemperature, without jeopardizing the qua ity of the spun material andof the-threads themselves, .it has become possible in accordance withthis invention, to submit the viscose to the spinning operation within alnultipleof the period referred to and within a period of maturit of 13,2 to '6, lossy thin threads of: ver igh degrees of fineness beingobtaine in this manner. .An

. is above or below the contents above referred to for severalpercentages. With equally favorable results the new process may beapplied for the manufacture of staple fibers up to the very finestsingle threads.

In the'practice of our" invention we may,

for instance, proceed as follows Example l.-2 kilograms of bleachedsulfite pulp are mercerized at ordinary temperature for'about ninetyminutes in abou 25 liters of soda liquor of 18 percent in which 315grams crystallized sodium sulphite have been dissolved; thedisintegrated comminuted alkali-cellulose is submitted to a preliminarymaturing in closed boxes at 22 degrees centigrade for about hours afterhaving been squeezed out to about 6.2 kilograms. Then thealkali-cellulose is treated with about 600 grams of carbonbisulfide atabout- 20 degrees cent. for some hours with gentle agitation, and thexanthate formed is dissolved into viscose by treatment with 2 kilogramssoda lye of 18%, and 10 kilograms of water at about 15 degrees C.

After repeated filtration the viscose is determined at a maturing stagebetween 13 and 7 by coagulation with ammoniumchloride solution accordingto Hottenroth this determination being effected by titrating, say twentygrams of viscose with a 10 percent solution of ammonium-chloride untilcoagulation .occurs, as described in Chemiker- Zeitung, Cothen, 1915,page 119; it is then injected in the quantity required for obtaining atiter or thread number of 125 deniers from a spinning nozzle having 30holes of one-tenth millimeter diameter, and into a spinning bath of 42degrees centigrade containing sodium-sulphate, and having an acidity offrom 15 to 16 percent sulphuric acid determined at 40 degrees .C. andat-a specific gravity of 1.459. The bundle of fibers obtained in thismanner is wound upon a reel or bobbin in the usual manner, having apulling velocity of 40 meters. The finished bobbin with the threadswound thereon is freed from acid and salt by washing it with water; itis then dried, twisted if desired, and submitted to further treatment asusual. The thread of artificial viscose silk is glossy afterdesulfuration. The single thread number or titer is about 4: deniers.

Example lI.-The xanthate of cellulose obtained as described in thefirstexample is dissolved at about 15 degrees centigrade with 9 kilograms ofwater in 3.7 kilograms of waste alkali liquor of 16.4 percent obtainedupon the mercerization or squeezing out of the alkali-cellulose, andcontaining soluble organic bodies and sulfite of sodium from thecellulose. The repeatedly filtered viscose in the quantity required forobtaining a titerthread number of 60 deniers is inje'ctedfrom a nozzlewith 40 holes of one tenth millimeter diameter each, and at anammoniumchloride maturity stage of between 13 and 6, into aspinningbath'of 42 degrees centigrade temperature which shows a density of 1.39observed at 40 degrees C. The bath contains from 15 to 16 percent ofsulphuric acid and enough sodium-sulphate to bring the specific gravityup to the required value. The thread obtained is treated as describedwith reference to Example I. The desulfurated thread is glossy, andpossesses an individual single thread number or titer of 1.5 deniers.

Certain diflerences in the contents of cellulose, alkali andcarbon-bisulfid, and cer tain variations of temperature are permissiblewithout interference with the process. The amount of sulfite added tothe viscose according to the procedure above described may be furtherincreased by separate additions at any suitable points of the process.

We claim 1. The process of producing artificial silk threads fromviscose, which consists in treating alkali-cellulose withcarbon-bisulfide in the presence of a reducing agent, dissolving thexanthogenate formed in alkali in the presence ofreducing agents, andinjecting the solution obtained into a solution of sodium sulphate-containing comparatively large amounts of sulphuric acid.

2. The. process of producing artificial silk threads from viscose,-which consists in treating alkali-cellulose with carbon bisulfide inthe presence of reducing agents, dissolving the xanthate produced in amixture of alkaline liquor with sodium sulphite, ripening the solution,and then injectingthe same into an acid setting and coagulating bath. i1

3. The process of producing artificial silk threads from viscose, whichconsists in treating alkali celluose with carbon bisulphide in thepresence of reducing agents, dissolving the xanthate formed in soda 1liquor cl-afizainin sulphite of alkali, and injecting the solutionobtained into a. strongly acid solution of sodium sulphate.

4. The process of producing objects from viscose, which consists intreating cellulose 1 with alkali in the presence of reducin agents,separating the alkali-cellulose obtained from the waste liquor, treatingthe alkali-cellulose with carbon-bisulphide, dissolving the xanthatethereby produced in said waste liquor, and introducing said solutioninto a setting and coagulating bath.

5. The process of producing ob ects from viscose, which consists intreating cellulose with alkali and sodium. sulphite, submitting thealkali-cellulose obtained to a prelimi nary maturing, separating thealkali-cellulose from the waste liquor, treating the alkalicellulosewith carbon-bisulphide, dissolving 'the xanthate thereby produced insaid waste liquor, ripening the solution obtained and introducing thesolution into a setting and coagulating bath.

6. The process of producing objects from viscose, which consists intreating cellulose with alkali and sodium-sulphite, separating it fromthe waste liquor, submitting the alkali-cellulose obtained to apreliminary maturing, treating the alkali-cellulose withcarbon-bisulphide, dissolving itin alkalisolntion containing sulphite ofalkali, ripening the solution of viscose obtained, and introducin it atan ammonium-chloride measure of between13 and 6 ripening stage into asetting and coagulating bath;

7 The process of roducing artificial silk from viscose, which consistsin treating alkali-cellulose with carbon-bisulphide in g the presence ofa reducing agent, dissolving the xanthogenate formed in alkali in thepresence of reducing agents, and treating the solution obtained with asetting bath.

8. The process of producing artificial silk material from viscose, whichconsists .in treating alkah-cellulose with carbon-bisuls phide andsoluble sulphite, dissolving the xanthogenate formed in alkali in thepresence of sulphite, and treating the solution obtained with a settingbath.

9; The process of preparing artificial-silkmaterial from viscose, whichconsists in treating cellulose with caustic-alkali-liquor in thepresence of soluble sulphite, removing the bulk of the liquid, andtreating the remaining mass, containing sulphite with carbon-bisulphide,and finally acting thereupon with a setting bath.

10. The process of preparing artificialsilk-material from viscose, whichconsists in treating cellulose with caustic-alkali-liquor in thepresence of soluble a'lkali-sulphite, removing the bulk of the liquid,treating the remaining mass in the presence of soluble sulphites withcarbon-bisulphide, dissolving the xanthogenate formed in alkali in thepresence of reducing agents, and treating the solution obtained with a.setting bath.

In testimony whereof we aifix our signatures.

- DR. L. HESSE.

DR. H. RATHERT.

